make reciprocal estimate code generation more flexible by adding command-line options (2nd try)

The first try (r238051) to land this was reverted due to bot failures
that were hopefully addressed by r238788.

This patch adds a TargetRecip class for processing many recip codegen possibilities.
The class is intended to handle both command-line options to llc as well
as options passed in from a front-end such as clang with the -mrecip option.

The x86 backend is updated to use the new functionality.
Only -mcpu=btver2 with -ffast-math should see a functional change from this patch.
All other x86 CPUs continue to *not* use reciprocal estimates by default with -ffast-math.

Differential Revision: http://reviews.llvm.org/D8982

llvm-svn: 238842

1 files changed, 0 insertions, 12 deletions

diff --git a/llvm/lib/Target/X86/X86Subtarget.h b/llvm/lib/Target/X86/X86Subtarget.h
index 455dd7744d7..27429d050bd 100644
--- a/llvm/lib/Target/X86/X86Subtarget.h
+++ b/llvm/lib/Target/X86/X86Subtarget.h
@@ -190,16 +190,6 @@ protected:
   /// True if INC and DEC instructions are slow when writing to flags
   bool SlowIncDec;
 
-  /// Use the RSQRT* instructions to optimize square root calculations.
-  /// For this to be profitable, the cost of FSQRT and FDIV must be
-  /// substantially higher than normal FP ops like FADD and FMUL.
-  bool UseSqrtEst;
-
-  /// Use the RCP* instructions to optimize FP division calculations.
-  /// For this to be profitable, the cost of FDIV must be
-  /// substantially higher than normal FP ops like FADD and FMUL.
-  bool UseReciprocalEst;
-
   /// Processor has AVX-512 PreFetch Instructions
   bool HasPFI;
 
@@ -377,8 +367,6 @@ public:
   bool LEAusesAG() const { return LEAUsesAG; }
   bool slowLEA() const { return SlowLEA; }
   bool slowIncDec() const { return SlowIncDec; }
-  bool useSqrtEst() const { return UseSqrtEst; }
-  bool useReciprocalEst() const { return UseReciprocalEst; }
   bool hasCDI() const { return HasCDI; }
   bool hasPFI() const { return HasPFI; }
   bool hasERI() const { return HasERI; }